Evaluating the effect of different combination of impression and pouring materials on marginal and internal adaptation of zirconia crowns / Evaluación del efecto de diferentes combinaciones de materiales de impresión y vertido en la adaptación marginal e interna de las coronas de circonio

Purpose: Two important factors in dental prosthesis are making an accurate impression and producing a suitable cast which represents the exact relationship between prepared tooth and oral structures. This study, aimed to investigate the effects of different combinations of impression and pouring materials on marginal and internal adaptation of premolar zirconia crowns. Material and Methods: Forty maxillary premolars were prepared considering round shoulder finish line. The impressions were made either by additional (Panasil) or condensation (Speedex) silicon, and poured by two different types of gypsum materials (Siladent or GC gypsum) (N=10). Zirconia crowns were fabricated using a CAD-CAM system. The crowns were cemented, and the samples were cut in bucco-lingual direction. Marginal and internal gaps were measured by stereomicroscope (×25). Results: The mean marginal gaps for Pansil-Siladent, Panasil-GC, Speedex-Siladent, and Speedex-GC were 141 µm, 143 µm, 131 µm, and 137 µm respectively. The internal gaps were 334 µm, 292 µm, 278 µm, and 257 µm respectively. The independent T-Student test showed no significant differences in average marginal or internal gap among various impression and gypsum materials or their interactions (p>0.05). Two-way ANOVA test showed no significant differences in maximum marginal or internal gap among various impression and gypsum materials and their interactions (p>0.05). Conclusion: The present study revealed no statistically significant difference in marginal/internal gap among crowns prepared using different combinations of impression-pouring materials evaluated.

Introducción: Dos factores importantes en la prótesis dental son hacer una impresión precisa y la producción de un modelo adecuado que represente la relación exacta entre el diente preparado y las estructuras orales. Este estudio, tuvo como objetivo investigar los efectos de diferentes combinaciones de materiales de impresión y vertido sobre la adaptación marginal e interna de coronas de zirconio premolar. Material y Métodos: Se prepararon cuarenta premolares maxilares considerando la línea de meta del hombro redondo. Las impresiones se realizaron con silicio adicional (Panasil) o de condensación (Speedex) y se vertieron con dos tipos diferentes de materiales de yeso (yeso Siladent o GC) (N = 10). Las coronas de zirconio se fabricaron utilizando el sistema CAD-CAM. Las coronas se cementaron y las muestras se cortaron en dirección buco-lingual. La brecha marginal e interna se midió con estereomicroscopio (×25). Resultados: Las brechas marginales medias para Pansil-Siladent, Panasil-GC, Speedex-Siladent y Speedex-GC fueron de 141µm, 143µm, 131µm y 137µm, respectivamente. Las brechas internas fueron 334µm, 292µm, 278µm y 257µm, respectivamente. La prueba de T-Student independiente no mostró diferencias significativas en la brecha marginal o interna promedio entre varios materiales de impresión y yeso o sus interacciones (p>0.05). La prueba ANOVA bidireccional no mostró diferencias significativas en el espacio marginal o interno máximo entre varios materiales de yeso y de impresión y sus interacciones (p>0.05). Conclusión: El presente estudio no reveló diferencias estadísticamente significativas en la brecha marginal/interna entre las coronas preparadas con diferentes combinaciones de materiales de impresión y vertido evaluados.

Estabilidade dimensional de moldes obtidos com alginato de armazenamento tardio / Dimensional stability of molds obtained with late storage alginate

Resumo Introdução Recentemente, vêm surgindo no mercado alguns alginatos de armazenamento prolongado. Não há, no entanto, um consenso na literatura a respeito da estabilidade dimensional destes materiais durante este armazenamento Objetivo Avaliar, por meio de método prático experimental, a estabilidade dimensional de um alginato de armazenamento tardio. Material e método O material de moldagem utilizado foi o alginato Hydrogum 5 (Zhermack). Uma matriz metálica cilíndrica foi utilizada para a realização das moldagens, com 38 mm de diâmetro externo, 30 mm de diâmetro interno e cuja superfície superior apresenta três linhas paralelas entre si com 25 mm de comprimento e 20, 50 e 75 µm de largura. Após o tempo de geleificação do material de moldagem, 16 moldes foram colocados em um umidificador e essas amostras foram fotografadas utilizando-se uma câmera digital (Canon EOS Rebel 3Ti, Canon) associada a um software para análise das imagens obtidas (ImageJ 1.52a, U.S. National Institutes of Health; DI). A calibragem da régua foi 10 cm e, posteriormente, três linhas foram medidas três vezes, para se obter uma média dos comprimentos das linhas. As amostras foram fotografadas nos seguintes intervalos: imediatamente, 24, 48, 72, 96 e 120 horas. Resultado Os dados mostraram diferenças estatisticamente significantes para o fator tempo quando comparada a leitura imediata com os demais períodos de tempo de leitura (p<0,001) e quando comparada a leitura após 24 h de armazenagem com os demais períodos de tempo (p<0,001). Não houve diferença estatística (p>0,05) quando os tempos de armazenamento de 48 h, 72 h, 96 h e 120 h foram comparados entre si. Todos os valores encontravam-se dentro dos valores preconizados pela ISO 21563:2013. Conclusão Os moldes dos alginatos testados podem ser armazenados por até cinco dias em 100% de umidade relativa.

Abstract Introduction Recently, some extended-pour alginate impression materials have been placed in the market. However, there is no consensus in the literature regarding the dimensional stability of these materials during these storage. Objective To evaluate, through the experimental model, the durability and velocity with respect to dimensional alteration, analyzing the material and detecting distortions. Material and method The material for molding in this test was alginate (Hydrogum 5, Zhermack). A cylindrical metallic matrix was used to make the moldings with: 38 mm of external diameter, 30 mm of internal diameter and superior of the upper series of the card 3d transport lines with each 25 mm in length and 20, 50 and 75μm in width. After the time of jellification / polymerization of the molding material, 16 molds were inserted in a doser and were photographed with a digital camera (Canon EOS Rebel 3Ti, Canon) associated with a software for analysis of sacred images (ImageJ 1.52a, US National Institutes of Health, DI). The calibration of the ruler was performed in 10 cm and then in 3 lines were means 3 (three) times to obtain a mean of the lengths of the lines. The photographs were taken at the following intervals: immediately, 24, 48, 72, 96 and 120 hours after being cast. Result The data were found when compared with the other parts of the reading time (p <0.001) and when compared to the execution after 24 hours of locomotion with the other parts of the time (p <0.001). The rest time of 48 hours, 72 hours, 96 hours and 120 hours were compared to each other. Conclusion The molds of the tested alginates can be stored for 5 days in 100% relative sauce.

The effect of prolonged storage and disinfection on the dimensional stability of 5 vinyl polyether silicone impression materials

PURPOSE: Vinyl polyether silicone (VPES) has a different composition from other elastomeric impression materials as it combines vinyl polysiloxane (VPS) and polyether (PE). Therefore, it is important to study its properties and behavior under different test conditions. This study investigated the dimensional stability of 5 VPES consistencies when stored for up to 2 weeks, with and without using a standard disinfection procedure. MATERIALS AND METHODS: 40 discs of each VPES consistency (total 200) were made using a stainless steel die and ring as described by ANSI /ADA specification No. 19. 20 discs of each material were immersed in a 2.5% buffered glutaraldehyde solution for 30 minutes. Dimensional stability measurements were calculated immediately after fabrication and repeated on the same discs after 7 and 14 days of storage. The data was analyzed using two-way ANOVA with a significance level set at α = 0.05. RESULTS: The discs mean contraction was below 0.5% at all test times ranging from 0.200 ± 0.014 to 0.325 ± 0.007. Repeated measures ANOVA showed a statistically significant difference after 2-week storage between the disinfected and non-disinfected groups (P < .001). Although there was no statistically significant difference between the materials at the time of fabrication, the contraction of the materials increased with storage for 1 and 2 weeks. CONCLUSION: The dimensional changes of VPES impression discs after disinfection and prolonged storage complied with ANSI/ADA standard. The tested VPES impression materials were dimensionally stable for clinical use after disinfection for 30 minutes in glutaraldehyde and storage for up to 2 weeks.

Effect of mixing method on the working time and setting time of alginate impression materials / 实用口腔医学杂志

Working time of normal setting impression materials was 71 (hand mixing,30 s),66 (Alghamix,20 s) and 53 (Algimax-Ⅱ,8 s) seconds respectively.Working time of fast setting impression materials was 56 (hand mixing,30 s) and 51 (Alghamix 20 s) seconds respectively.Setting time of normal setting impression materials was 163 (hand mixing,30 s),160(Alghamix 20 s) and 124(Algimax-Ⅱ,8 s)seconds respectively.Setting time of fast setting impression materials were 131 (hand mixing,30 s) and121 (Alghamix 20 s) seconds.The working and setting time of normal setting impression materials mixed by hand mixing(30 s) and auto-mixing (Alghamix 20 s;Algimax-Ⅱ,8 s) and fast setting impression materials mixed by hand mixing(30 s) and with auto-mixing using Alghamix (20 s) may satisfly clinical requirement.

Accuracy of partially edentulous arch impressions obtained from different alginates and storage times

Purposes: This study aimed to assess the dimensional accuracy of five commercial alginates verified in stone casts. Methods: Each alginate impression (Cavex ColorChange, Cavex Holland BV; Jeltrate Plus, Dentsply; Hydrogum, Zhermack; Kromopan 100, Lascod; Ezact Kromm, Vigodent) was performed on partially edentulous standard stainless steel mandibular arch cast with reference points on teeth 33, 43, 37 and 47. On the stainless steel cast, the anteroposterior (33-37 and 43-47) and transverse (33-43 and 37-47) distances were measured in a stereomicroscope at 30x magnification and 0.5 µm accuracy. The distances between these points were measured three times, obtaining an average, which was analyzed statistically and compared with the distances obtained from the stone casts. For each alginate the casts were poured gypsum (n = 5) immediately and after a period of 1, 2, 3 and 5 days of the impression procedure. Results: The dimensional accuracy values of stone and stainless steel casts were analyzed statistically by two-way ANOVA and Tukey's test (α=0.05). The results showed significant differences between the alginates; however, no differences in dimensional accuracy were found among the different storage times of alginate impression. Conclusions: It can be concluded that the alginate impressions can be stored for up to 5 days (AU)

Ranula – threefold habituation.

Intraoral swellings present as a diagnostic challenge to the clinician, the most bourgeois being mucocele & ranula. An intraoral ranula has been defined as a retention cyst due to ductal obstruction & fluid retention of the sublingual salivary gland on the floor of the mouth. The name “ranula” has been derived from the latin word “Rana” meaning “Frog.” We hereby report a case of triennial recurrent ranula located in the floor of mouth, treated successfully by surgical excision by injecting an irreversible impression material to delineate the cystic lining of the lesion, after which the patient recovered unvariedly.

Empirical study of alginate impression materials by customized proportioning system

PURPOSE: Alginate mixers available in the market do not have the automatic proportioning unit. In this study, an automatic proportioning unit for the alginate mixer and controller software were designed and produced for a new automatic proportioning unit. With this device, it was ensured that proportioning operation could arrange weight-based alginate impression materials. MATERIALS AND METHODS: The variation of coefficient in the tested groups was compared with the manual proportioning. Compression tension and tear tests were conducted to determine the mechanical properties of alginate impression materials. The experimental data were statistically analyzed using one way ANOVA and Tukey test at the 0.05 level of significance. RESULTS: No statistically significant differences in modulus of elastisity (P>0.3), tensional/compresional strength (P>0.3), resilience (P>0.2), strain in failure (P>0.4), and tear energy (P>0.7) of alginate impression materials were seen. However, a decrease in the standard deviation of tested groups was observed when the customized machine was used. To verify the efficiency of the system, powder and powder/water mixing were weighed and significant decrease was observed. CONCLUSION: It was possible to obtain more mechanically stable alginate impression materials by using the custom-made proportioning unit.

Transferência precisa da morfologia do tecido mole peri-implantar em prótese anterior: relato de caso / Accurate transposition of peri-implant soft tissue morphology in anterior prosthesis: case report

O perfil de emergência em próteses implantossuportadas é a porção da restauração que emerge coronalmente do implante até a gengiva marginal livre, visando conferir suporte e estabilidade ao tecido mole peri-implantar, mimetizando o dente natural. As restaurações com contornos apropriados têm um efeito significativo na higiene bucal, saúde do tecido peri-implantar e estética. O maior desafio para a confecção de próteses implantossuportadas definitivas está na duplicação do perfil de emergência obtido com a prótese provisória para o modelo de trabalho, sendo que há várias técnicas publicadas, porém não há um consenso na literatura sobre qual método é mais preciso. O objetivo do presente estudo é apresentar, por meio do relato de um caso clínico, uma técnica de moldagem do perfil de emergência e tecido peri-implantar...

The emergence profile for implant-supported prostheses is the portion of the restoration that emerges coronally from the implant to the free gingival margin, giving support and stability to peri-implant soft tissues and mimicking the natural tooth. Restorations with appropriate contour have a significant effect on oral hygiene, health and esthetics of peri-implant tissues. The greatest challenge involved in manufacturing permanent prosthesis is the duplication of the emergence profile obtained with the provisional restoration secured to the cast. Several techniques have been published, but no consensus has been reached on the literature regarding which method is the most accurate. The objective of this study is to present a technique for molding the emergency profile and peri-implant tissues by presenting a clinical case...

Magic with Simple Materials-Admixture (Modified Impression Compound the Golden Standard)

Making a good and an accurate impression is an art and science. Handling the properties of material and their selection is very important. An ideal impression material requires rigidity for dimensional stability and adequate flow for accuracy with an allowance for registering and finer adjustments. Incorporation of greenstick compound into impression compound makes it almost the perfect material of choice.

Effect of 3 different medicament on dimensional stability and surface detail reproduction of polyvinyl siloxane impression material.

Aim:Surface detail reproduction and dimensional stability of Poly vinyl siloxane impression material is most important property for final success of fixed partial denture. Purpose: This study was carried out to determine the effect of retraction cord medicaments (epinephrine, aluminum chloride and ferric sulfate) on the dimensional accuracy and surface detail reproduction of polyvinyl siloxane impressions. Method and materials: Polyvinyl siloxane impressions were made of standardized metal dies (American Dental Association [ADA] specification No. 19) and was treated with 1 of the 3 retraction cord medicaments. Dimensional accuracy was evaluated by comparing the average length of a line in the impressions to the standard die. Surface detail reproduction was evaluated by viewing the impressions under low-angle illumination at 10X magnification. Reproduction was considered satisfactory if 2 of 3 horizontal lines were reproduced continuously. The dies were also evaluated under the microscope before the impression was made. Results: The medicaments did not significantly affect the dimensional stability. Aluminum chloride and ferric sulfate had an adverse effect on surface detail reproduction. Epinephrine had no effect. Discussion: The changes in dimensional accuracy were within ADA guidelines, the surface detail reproduction was modified such that the impression would be considered clinically unacceptable. For optimal results, care must be taken to remove all traces of these retraction cord medicaments prior to recording of a polyvinyl siloxane impression.

A Simplified Approach For Rehabilitation of An Edentulous Patient With Oral Submucous Fibrosis - A Clinical Report.

Oral sub mucous fibrosis is an insidious chronic disease and a precancerous condition, affecting any part of the oral cavity and sometimes the pharynx. Management of patient with oral sub mucous fibrosis presents difficulties at all stages, from the preliminary impressions to fabrication of prostheses. This article will present simplified approach for management of a 61year old male edentulous patient with oral sub mucous fibrosis. So that final outcome may be achieved.

Influence of retentive areas associated to onlay preparations on the dimensional stability of silicone impression materials

This study evaluated the effect of retentive areas on onlay preparations on the dimensional alterations in condensation and addition silicone materials. A standard model with an onlay preparation was made. Each impression material was used through the double or simultaneous impression technique (n=25), resulting in a hundred impressions of the same model. Impressions were poured with type IV dental stone. Digital images were taken with a light microscope and the distances between the reference points created on the plaster dies were compared with the ones on the standard model. In the occlusal, mesial-medium and mesial-cervical segments, the double impression (DI) with condensation silicone presented similar values compared to the standard model. The values of the addition silicone with DI were similar to the standard model only in the mesial-occlusal segment. In the other segments (distal-cervical, distal-medium and distal-occlusal), all groups were statistically different from the control. It could be concluded that addition and condensation silicone impressions provided plaster dies with significant dimensional alterations in most of the evaluated areas when compared to the standard model. The retentive areas related to the onlay preparation influenced the dimensional stability of the addition and condensation silicone impressions.

Este estudo avaliou as alteracoes dimensionais de silicones de condensacao e adicao usados em duas tecnicas como resultado de areas retentivas de preparos do tipo onlay. Um modelo padrao foi feito e vinte e cinco moldagens realizadas com os dois materiais, atraves da tecnica de dupla impressao ou impressao simultanea, e cada material resultou em 50 modelos de gesso. Imagens digitais foram feitas com um microscopio de luz e as distancias entre os pontos de referencia criados no modelo de gesso foram comparados aos pontos de referencia no modelo padrao. Nos segmentos oclusais, medio-mesial e cervico-mesial, a tecnica de dupla impressao (DI) com silicone de condensacao apresentou valores similares comparados ao modelo padrao. Os valores do silicone de adicao com DI foram similares ao modelo padrao somente no segmento mesio-oclusal. Nos outros segmentos (disto-cervical, medio-distal e disto-oclusal), todos os grupos foram estatisticamente diferentes do controle. Pode- se concluir que moldagens com silicone de adicao e condensacao conferem modelos de gesso com alteracoes dimensionais significativas na maioria das areas avaliadas, quando comparadas ao modelo padrao. As areas retentivas relacionadas ao preparo de onlay influenciaram na estabilidade dimensional das moldagens atraves dos silicones de condensacao e adicao.

Drying time of tray adhesive for adequate tensile bond strength between polyvinylsiloxane impression and tray resin material

STATEMENT OF PROBLEM: Use of custom tray and tray adhesive is clinically recommended for elastomeric impression material. However there is not clear mention of drying time of tray adhesive in achieving appropriate bonding strength of tray material and impression material. PURPOSE: This study is to investigate an appropriate drying time of tray adhesives by evaluating tensile bonding strength between two types of polyvinylsiloxane impression materials and resin tray, according to various drying time intervals of tray adhesives, and with different manufacturing company combination of impression material and tray adhesive. MATERIAL AND METHODS: Adhesives used in this study were Silfix (Dentsply Caulk, Milford, Del, USA) and VPS Tray Adhesive (3M ESPE, Seefeld, Germany) and impression materials were Aquasil Ultra (monophase regular set, Dentsply Caulk, Milford, Del, USA) and Imprint II Garant (regular body, 3M ESPE, Seefeld, Germany). They were used combinations from the same manufacture and exchanged combinations of the two. The drying time was designed to air dry, 5 minutes, 10 minutes, 15 minutes, 20 minutes, and 25 minutes. Total 240 of test specimens were prepared by auto-polymerizing tray material (Instant Tray Mix, Lang, Wheeling, Il, USA) with 10 specimens in each group. The specimens were placed in the Universal Testing machine (Instron, model 3366, Instron Corp, University avenue, Nowood, MA, USA) to perform the tensile test (cross head speed 5 mm/min). The statistically efficient drying time was evaluated through ANOVA and Scheffe test. All the tests were performed at 95% confidence level. RESULTS: The results revealed that at least 10 minutes is needed for Silfix-Aquasil, and 15 minutes for VPS Tray Adhesive-Imprint II, to attain an appropriate tensile bonding strength. VPS Tray Adhesive-Imprint II had a superior tensile bonding strength when compared to Silfix-Aquasil over 15 minutes. Silfix-Aquasil had a superior bonding strength to VPS Tray Adhesive-Aquasil, and VPS Tray Adhesive-Imprint II had a superior tensile bonding strength to Silfix-Imprint II at all drying periods. CONCLUSION: Significant increase in tensile bonding strength with Silfix-Aquasil and VPS Tray adhesive-Imprint II combination until 10 and 15 minutes respectively. Tray adhesive-impression material combination from the same company presented higher tensile bonding strength at all drying time intervals than when using tray adhesive-impression material of different manufactures.

An evaluation of the time-dependent dimensional stability of elastomeric impression materials / 대한치과보철학회지

Statement of Problem: The accuracy and dimensional stability of elastomeric impression materials have been the subject of numerous investigation. Few studies have addressed the effect of changes in time on the dimensional stability of impression materials. Purpose: The purpose of this investigation was to evaluate the effects of elastomeric impression materials and storage time on dimensional stability. Materials and methods: A total of 75 impressions were made of epoxy resin dies mimicked prepared 3-unit fixed partial denture. The dies had 1 buccolingual, 1 mesiodistal and 1 occlusogingival lines and interpreped dot. Impression materials investigated included two polyether impression materials and three polyvinylsiloxane impression material. 15 specimens were made of each impression material and poured by type IV stone over times(30 minutes, 24 hours, 72 hours) after mixing; the same examiner measured each specimen 3 times at a magnification of 3.5*. All statistical tests were performed with the level of significance set at .05. Results: The results indicated that significant difference at any measuring point of stone dies of the polyvinylsiloxane and polyether impression materials when measurements at 30 minutes, 24hours, and 72 hours were compared; the length of measuring point increased significantly as time passed by. However, this result is not significant clinically. Analysis also showed significant differences at any measuring point when polyvinylsiloxane and polyether impression materials were compared and significant differences clinically. Conclusion: Under the conditions of this study, the shrinkage rate of the polyvinylsiloxane and polyether impression materials significantly increased as time passed by. The polyether impression materials showed higher shrinkage significantly, while the shrinkage rate of all five materials showed a significant time-dependent increase.

Tensile bond strength between elastomeric impression materials and tray resins depending on the thickness of the tray adhesive / 대한치과보철학회지

STATEMENT OF PROBLEM: Elastomeric impression materials have been widely used to obtain an accurate impression. However there have not been enough studies on the influence of the thickness of the tray adhesives on the bonding strength between the trays and the elastomeric impression materials. PURPOSE: In order to understand the relationship between the thickness of the tray adhesive and the tensile bond strength and to suggest the thickness at which the bonding strength is strongest, tensile bond strength related to the thickness of adhesives of 3 different elastomeric impression materials were tested. MATERIALS AND METHODS: 3 impression materials, Permlastic(R) Regular Set(Kerr Corp., Romulus, Michigan, U.S.A.), Impregum(TM) Penta(TM)(3M ESPE, Seefeld, Germany), and Aquasil Ultra Monophase Regular Set Smart Wetting(R) (Dentsply Caulk, Milford, Delaware, U.S.A.), were used in this study, and tray adhesives from the same manufacturers of the impression materials were used, which were Rubber Base Adhesive, Polyether Adhesive, and Silfix, respectively. The tray specimens were prepared by autopolymerizing the tray material(Instant Tray Mix, Lang, Wheeling, Illinois, U.S.A.), and a PVC pipe was used to house the impression material. In group A, tray adhesives were applied in multiple thin layers of 1 to 5 and in group B, adhesives were applied only once, in the thickness equivalent to several applications. Lightness(L*) of the adhesion surface was measured with a spectrophotometer (CM-3500d, Konica Minolta, Sakai, Osaka, Japan). The tensile bond strength of the elastomeric impression material and the tray resin was measured with universal materials testing machines(Instron, Model 3366, Instron Corp, Nowood, Massachusetts, U.S.A.). A formula between the number of adhesive application layers and the lightness of the adhesion surface was deduced in group A, and the number of adhesive layers in group B was estimated by applying the lightness(L*) to the deduced formula. RESULTS: 1. In group A, a statistically significant increase in tensile bond strength appeared when the number of application layers increased from 1 to 2 and from 4 to 5, and no significant difference was present between 2, 3, and 4 layers in Permlastic. In Impregum, the tensile bond strength was significantly increased when the number of adhesive layers increased from 1 to 3, but no significant difference after 3 layers. In Aquasil, the tensile bond strength significantly increased as the number of application layers increased up to 4 but showed no significant difference between 4 and 5. 2. In group B, the tensile bond strength was decreased when the thickness of the adhesive increased in Permlastic. Impregum showed an increased tensile bond strength when the thickness of the adhesive was increased. In Aquasil, the tensile bond strength increased as the number of adhesive application layers increased up to approximately 2.5 layers but it sharply decreased after approximately 4.5. CONCLUSION: From the study, the common idea that it is better to apply a thin and single coat of tray adhesive needs correction in more detailed ways, and instructions on some of the tray adhesives should be reconsidered since there were several cases in which the tensile bond strength increased according to the increase in the thickness of the adhesives.

WETTABILITY OF POLYVINYLSILOXANE IMPRESSION MATERIALS AND IMPROVED STONE MATERIALS / 대한치과보철학회지

Wettability of addition silicone impression material is very important property for making an accurate restoration. This study examined the impression quality in clinical condition and the wet tability of impression and die material. Four commercially available addition silicone impression material (Express, Examix, Contrast, Perfect) and three die materials (Die-Keen, Vel-Mix, FujiRock) were studied. A total of 50 putty/wash and heavy body/wash impressions of wet intact permanent molar teeth were examined for definition of the gingival sulcus reproduction and then classified in quality ranking. The percentage of the sulcus reproduction ability of each material was calculated from the sulcus depths of cross-sectioned epoxy resin casts from the impressions and clinically measured sulcus depths. The same impression materials were used to produce 3 groups of die stone casts form void entrapment die had been exposed to milk. Voids in the impression. body and stone casts were counted under a stereoscopic microscope. From the experiment, the following results were obtained 1. Sulcus reproduction ability of additional silicone impression material were diminished in order of Express, Examix, Perfect, Contrast. The significant difference was found between Perfect and other material. Heavy body/wash combination was superior to putty/wash method in Perfect impression material. 2. In direct observation, bontrast showed least void in impression body but correlations were not found between sulcus reproduction and void production. 3. In void entrapment laboratory test, wettability were diminished in order of Examix, Contrast, Express, Perfect. Clinical impression recording seems not to correlate with laboratory test. 4. The wettability of die material to impression material was not different in Express, Examix, Contrast. But, in Perfect, Die-Keen had superior wettability to others.

The effect of glutaraldehyde disinfectant on the dimension stability of four high polymer impression materials / 实用口腔医学杂志

Objective:To measure the effect of disinfection on dimension stability of four high polymer impression materials which were separately immersed in 20 ml/L glutaraldehyde solution.Methods:Fifteen plaster replication models of four high polymer impression materials(Impregum Penta polyether, Express-Putty silicone, Silagum-Putty silicone, GC EXAFINE silicone) were made on the same metal master cast respectively. Vertical and horizontal dimensions between landmarks on the masters and plaster casts were measured with an optical microscope,one-way ANOVA was used to compare the measurements among the materials.Results:The difference between the masters and Casts in horizontal distances measured on Express-Putty silicone impression material produced models was longer than those on other high polymer impression materials produced ones after disinfection for 20 minutes and beyond clinical requirement. Compared with metal master cast, the difference became significant when these four silicone impression materials were disinfected for 40 minutes. Conclusion: Among the four kinds of impression materials, the Express-Putty silicone material is relatively the most accurate one after disinfection for 20 minutes.

The bacteriostasis effect and the influences to copy accuracy of alginate impression material spatulated with bromogeramine / 重庆医科大学学报

0.05),respectively.Conclusion:Alginate impression material mixed with bromogeramine(0.40%) had some bacteriostatic effect on bacteria except pseudomonas aeruginosa,and it has no effect on the impression accuracy.It could be an ideal disinfection method for clinical use.

Study on bacteriostatic efficacy of alginate impression materials impregnated with bromogeramine / 重庆医科大学学报

Objective:To observe the bacteriostatic efficacy of bromogeramine of different concentrations made with potassium alginate impression materials.Methods:Based on the methods described in"Disinfection Technical Guidelines,2002 ed‘the second chapter-xxxx’"(Ministry of Public Health of the People’s Republic of China),the bacteriostatic efficacy was evaluated through measuring the size of inhibition zone formed by mixing bromogeramine with potassium alginate impression material.Results:Bromogeramine of any concentration had no effect on Pseudomonas aeruginosa.When the concentration of bromogeramine was above 0.4 mg/ml,the size of bacterio- static ring did not change.However,when the concentration increased to 0.05%,0.1%,0.2%,or 0.4%,the diameter of the inhibition zone was increasinly enlarged.Conclusions:Bromogeramine of certain concentration had some bacteriostatic effect on bacteria except pseudomonas aeruginosa.Besides,the bacteriostatic efficacy increased with the concentration increasing,but it did not change when the concentration of bromogeramine was above 0.4 mg/ml.

Study on modified method of making oral impression while patients wearing fixed appliances / 重庆医科大学学报

Objective:To modify the method of making oral impression and improve the successful rate.Methods:Rubber band was used to fill in the brackets before making oral impression.Two kinds of ways,the modified and the traditional,were used for each patient.Then the successful rate was compared between two groups.Results:There is statistically significant difference in the successful rate between the traditional group and the modified group ( P